The Kingdom of the Two Sicilies lasted from 1816 until 1860, when it was annexed by the Kingdom of Sardinia, which eventually became the Kingdom of Italy in 1861. The capital of the Two Sicilies was in Naples and was commonly referred to in English as the "Kingdom of Naples". The kingdom extended over the Mezzogiorno (the southern part of mainland Italy) and the island of Sicily. Jordan Lancaster notes that the integration of the Kingdom of the Two Sicilies into the Kingdom of Italy changed the status of Naples forever: "Abject poverty meant that, throughout Naples and Southern Italy, thousands decided to leave in search of a better future." Many went to the United States, Australia and Argentina.[3] The kingdom was heavily agricultural, like the other Italian states;[4] the church owned 50–65% of the land by 1750.[5]

The name "Two Sicilies" originated from the division of the medieval Kingdom of Sicily. Until 1285, the island of Sicily and the Mezzogiorno each formed part of the Kingdom of Sicily. As a result of the War of the Sicilian Vespers (1282-1302),[6] the King of Sicily lost the island of Sicily (also called Trinacria) to the Crown of Aragon, but remained ruler over the peninsular part of the realm. Although his territory became known as the Kingdom of Naples, he and his successors never gave up the title of "King of Sicily" and they officially referred to their realm as the "Kingdom of Sicily". At the same time, the Aragonese rulers of the island of Sicily called their realm the "Kingdom of Sicily" as well. Thus, formally, there were two kingdoms calling themselves "Sicily":[6] hence, the Two Sicilies.

The Kingdom of the Two Sicilies resulted from the unification of the Kingdom of Sicily with the Kingdom of Naples (called the Kingdom of Peninsular Sicily), by King Alfonso V of Aragon in 1442. The two states had functioned as separate realms since the War of the Sicilian Vespers in 1282. At the death of King Alfonso in 1458, the kingdom became divided between his brother John II of Aragon, who kept the island of Sicily, and his illegitimate son Ferdinand, who became King of Naples.

In 1734, Charles, Duke of Parma, son of Philip V of Spain, took the Sicilian crown from the Austrians and became Charles VII & V, giving Parma to his younger brother, Philip. In 1759, Charles became King Carlos III of Spain and resigned Sicily and Naples to his younger son, who became Ferdinand III of Sicily and Ferdinand IV of Naples, later crowned Ferdinand I of the Two Sicilies in 1816. Apart from an interruption under Napoleon, the Kingdom of the Two Sicilies remained under the Bourbon line (Bourbon Duo-Sicilie) continually until 1860.

In January 1799, Napoleon Bonaparte, in the name of the French Republic, captured Naples and proclaimed the Parthenopaean Republic, a French client state, as successor to the kingdom. King Ferdinand fled from Naples to Sicily until June of that year. In 1806, Napoleon, by then French Emperor, again dethroned King Ferdinand and appointed his brother, Joseph Bonaparte, as King of Naples. In the Edict of Bayonne of 1808 Napoleon moved Joseph to Spain and appointed their brother-in-law, Joachim Murat, as King of the Two Sicilies, though this only meant control of the mainland portion of the kingdom.[8][9] Throughout this Napoleonic interruption, King Ferdinand remained in Sicily, with Palermo as his capital.

The state existed in that form from 1130 until 1285. In the period of the Capetian House of Anjou during the reign (1266-1285) of King Charles I, the kingdom was split by the War of the Sicilian Vespers of 1282-1302.[6] Charles, who was of French origin, lost Sicily proper to the House of Barcelona, who were Aragonese and Catalan, after they were able to gain the support of the natives. Charles remained king over the peninsular part of the realm, thereafter informally known as the Kingdom of Naples. Officially Charles never gave up the title of "The Kingdom of Sicily", thus there existed two separate kingdoms calling themselves "Sicily".[6]

Alfonso V described the geographical area in Latin as Utriusque Siciliæ, meaning "of both Sicilies", which is the title he used.[11][not in citation given] After the death of Alfonso, both remained under direct rule from the Crown of Aragon, but Naples had a different Aragonese king from the island of Sicily from 1458 until 1501. For a brief period Naples was controlled by a different power other than Sicily, in the form of French king Louis XII of France who took the mainland kingdom and held it for around three years. After the Battle of Garigliano led by last Aragonese king Ferdinand II of Aragon, the two areas were once again under control of the same power and exactly the same king.

His son Ferdinand then became king of the two kingdoms so as to maintain them as separate realms as required by the treaties restoring the junior Spanish royalty to the southern Italian kingdoms. Ferdinand was highly popular with the poorest class. Ferdinand's reign was highly eventful. For a brief period the Parthenopaean Republic controled Naples with the support of those who supported the French Revolution. However, a counter-revolutionary army of the poorest class retook Naples in order to restore royal power.[13]

Ferdinand fled to his other kingdom, on the island of Sicily itself. Here the alliance he had previously made with George III of the United Kingdom and Tory Prime Minister the Earl of Liverpool saved him. The British protected Ferdinand and the island of Sicily from Napoleonic conquest with the presence of a powerful Royal Navy fleet.[15]

Back on the mainland, Joachim Murat had become the second Bonapartist king. In the Edict of Bayonne he was named as "King of the Two Sicilies",[8] though de facto he never actually held the island of Sicily where Ferdinand was, and is usually referred to as just the King of Naples.[16] Murat actually switched sides for a while, abandoning the Grand Army after the disastrous Battle of Leipzig in an attempt to save his Neapolitan throne. However, as the Congress of Vienna progressed, tensions arose as there was strong pressure to restore Ferdinand to the Neapolitan kingdom as well as keeping his Sicilian one.[14] Murat returned to Napoleon and together they declared war on the Austrian Empire, leading to the Neapolitan War in March 1815. Ferdinand and his allies Austria, Britain and Tuscany were victorious, restoring him to his Neapolitan throne. To avoid further French attempts, it was agreed at the Congress of Vienna that Ferdinand would reunite his kingdom.

Between 1816 and 1848, the island of Sicily experienced three popular revolts against Bourbon rule, including the revolution of independence of 1848, when the island was fully independent of Bourbon control for 16 months.

In 1861 Sicily was invaded by a corps of volunteers, led by Giuseppe Garibaldi from the Kingdom of Sardinia. They successfully conquered the Kingdom of the Two Sicilies.

According to Francesco Saverio Nitti writing in the 1890s, the kingdom had 443.3 million golden lire (about 65.7% of all the money circulating in the peninsula), more than the other Italian states. However, according to some historians, this was the poorest region of Italy for the inhabitants.[19]

Industry was much less important than agriculture. One of the most important industrial complexes in the kingdom was the Shipyard of Castellammare di Stabia, which employed 1800 workers. The engineering factory of Pietrarsa, was he largest industrial plant in the Italian peninsula producing tools, cannons, rails, locomotives. The complex also included a school for train drivers, and naval engineers and thanks to this school, the kingdom was able to replace the English personnel which was necessary until then. The first steamboat with screw propulsion known in the Mediterranean Sea is the "Giglio delle Onde", with mail delivery and passenger transport purposes after 1847.

In Calabria were located the Fonderia Ferdinandea was a large foundry where cast iron was produced. The Reali ferriere ed Officine di Mongiana was an iron foundry and weapons factory. Founded in 1770, it employed 1600 workers in 1860 and closed in 1880. In Sicily (near Catania and Agrigento), there sulphur was mined for gunpowder. The Sicilian mines were able to satisfy most of the sulphur world demand. Silk cloth production was focused in San Leucio (near Caserta). The region of Basilicata also had several mills in Potenza and San Chirico Raparo, where cotton, wool and silk were processed. Food processing was widespread especially near Naples (Torre Annunziata and Gragnano); much pasta was exported.

With all of its major cities boasting successful ports, transport and trade in the Kingdom of the Two Sicilies was most efficiently conducted by sea. The Kingdom possessed the largest merchant fleet in the Mediterranean. Urban road conditions were to the best European standards, by 1839, the main streets of Naples were gas-lit. Efforts were made to tackle the tough mountainous terrain, Ferdinand II built the cliff-top road along the Sorrentine peninsula. Road conditions in the interior and hinterland areas of the kingdom made internal trade difficult. The first railways and iron-suspension bridges in Italy were developed in the south, as was the first overland electric telegraph cable.

The kingdom achieved several scientific and technological accomplishments, such as the first steamboat in the Mediterrean Sea (1818), built in the shipyard of Stanislao Filosa al ponte di Vigliena, near Naples, and the first railway in the Italian peninsula (1839), which connected Naples to Portici. However, until the Italian unification, the railway development was highly limited. In the year 1859, the kingdom had only 99 kilometers of rails, compared to the 800 kilometers of Piedmont. This was because the kingdom could count on a very large and efficient merchant navy, which was able to compensate for the need for railways. Also, southern landscape was mainly mountainous making the process of building railways quite difficult, as building railway tunnels was much harder at the time. However, the first railway tunnel in the world was built there. Among the other achievements, one worth mentioning is the first suspension bridge in Continental Europe (1832), the first gaslight in Italy (1839), the first volcano observatory in the world, l'Osservatorio Vesuviano (1841), the first and actual archaeological excavations in the world( in the ancient cities of Pompei and Ercolano), the first faculty of Economics in Europe and the first faculty of Astronomy in Italy. The first suspension bridge, built in iron, the "Real Ferdinando" on the river Garigliano and it was built in the Reali Ferriere factory and Weapons factory in Mongiana. The rails for the first Italian railways were built in Mongiana as well. All the rails of the old railways that went from the south to as far as Bologna were built in Mongiana. Naples was the most populated city in Italy, and the third most populated city in Europe.[citation needed]

Some Sovereigns continued to maintain diplomatic relations with the exiled Court, including the Emperor of Austria, the Kings of Bavaria, Württemberg and Hanover, the Queen of Spain, the Emperor of Russia, and the Papacy.[when?]

...Here present is His Royal Highness Prince Don Carlo our dearest loved Son and he has declared that he shall be entering into marriage with Her Royal Highness the Infanta Doña Maria Mercedes, Princess of the Asturias, and assuming by that marriage the nationality and quality of Spanish Prince, intends to renounce, and by this present act solemnly renounces for Himself and for his Heirs and Successors to any right and rights to the eventual succession to the Crown of the Two Sicilies and to all the Properties of the Royal House found in Italy and elsewhere and this according to our laws, constitutions and customs of the Family and in execution of the Pragmatic Decree of King Charles III, Our August ancestor, of the 6th October 1759, to whose prescriptions he declares freely and explicitly to subscribe to and obey.[20]

The laws of the deposed Sicilian dynasty and Spain's Pragmatic Decree required a renunciation to prevent a union of the Crown of the Two Sicilies in the person of the King of Spain or his heir apparent, which could have happened in the event of a restoration, however unlikely. Most theories advanced to suggest that the 1900 renunciation was in some way unnecessary have been formulated long after the fact.[citation needed]

Prince Carlo's son, Infante Alfonso, became the senior male of the house on the death of his uncle, Ferdinando Pio, Duke of Calabria, in 1960 and was proclaimed Head of the Royal House of the Two Sicilies, with the recognition of the Heads of the royal houses of Spain, Parma and Portugal, and the senior line (Bourbon) pretender to the throne of France. Prince Carlo and his descendants continued to be included as Princes of the Two Sicilies in the Almanach de Gotha from 1901–44, and in the Libro d'Oro of the Italian Nobility from the first edition in 1907 until 1964, at which time the editor came out in support of the cadet line claimant. Infante Don Alfonso took the title of Duke of Calabria, considering that the title of Duke of Castro (a Farnese inheritance) had been lost with the sale of the last portions of the duchy to the Italian government in 1941 (a sale from which Prince Carlo received his portion of the proceeds, along with his brothers and sisters, although if the alleged renunciation of 1900 had been valid he would not have been entitled to do so). Carlo married as his second wife, in 1907, Princess Louise of Orléans, and by her had a son (Carlos, killed in the Spanish Civil War) and three daughters (of whom Princess Maria Mercedes married Juan, Count of Barcelona and was the mother of King Juan Carlos I of Spain, and Princess Esperanza married Prince Pedro Gastão of Orléans-Braganza). The descent in the senior line is as follows:

The rest of the Bourbon-Two Sicilies family rejected Alfonso's claims, however, and recognized Ranieri, the next surviving brother of Ferdinando Pius, as head of the house. Ranieri took the style of "Duke of Castro" as his title of pretence. The representatives of the junior branch are as follows:

Description of the arms appearing in the flag. Corrections: the upper part of the block marked "Flanders" is Burgundy Ancient; Burgundy Modern (as it is called in English; shown here as New Burgundy) includes a red-and-white border; the block marked "Aragon Two Sicilies" is only for Sicily proper (the other "Sicily" being the Angevin kingdom of Naples).